It might have been the greatest upset in presidential election history. Democratic incumbent Harry S. Truman defeated his Republican challenger, Governor Thomas E. Dewey of New York. He won by just two million total votes. The date was November 2, 1948 – 68 years ago today.

In the days preceding the vote, political analysts and polls were so behind Dewey that on election night, long before all the votes were counted, the Chicago Tribune published an early edition with the banner headline, “DEWEY DEFEATS TRUMAN.”

Harry Truman was thrust into the presidency by Franklin D. Roosevelt’s death in 1945. Approaching the 1948 presidential election, he seemed to stand a slim chance of retaining the White House. Truman, a one-time farmer who was elevated to the pinnacle of American politics because of his reputation for honesty and integrity, won the nation’s affection, and he narrowly won a second term.

This is good news for Donald Trump. The candidate who is behind in the polls always says, “Polls don’t vote; people do.” And they say, “The only poll that counts is the one they do on election day.”

But in every election since Truman’s the polls had it right. That would include 1952 and 1956 (Eisenhower); 1960 (Kennedy); 1964 (Johnson); 1968 and 1972 (Nixon); 1976 (Carter); 1980 and 1984 (Reagan); 1988 (Bush); 1992 and 1996 (Clinton); 2000 and 2004 (Bush); and 2008 and 2012 (Obama).

Trump is hoping that in six days history repeats itself – but not recent history.